What is the main role of the Angle of Attack of an airplane, as in mainstream explanation of lift?

Question

The question is conceptual and simple, it needs no more information to answer it. And I wish not to influence the answerer.

Answer 1

For simplicity, we start with a symmetrical airfoil.

The angle of attack modulates the amount of lift the wing will generate at a given airspeed & air density. At zero AoA, zero lift is generated. The amount of lift increases with increasing AoA up to the point of flow separation, where the amount of lift stops climbing and falls off (but not to zero).

If we look at the momentum explanation for lift, increasing the AoA tips the momentum vectors of air parcels further downward, increasing the magnitude of the reaction force on the wing- which constitutes lift.

If we look at the pressure distribution explanation, greater AoA increases the pressure difference between the top surface of the wing and the bottom surface, which means more lift.

As explained elsewhere, the true cause of lift must take both of these simplified mechanisms into account along with such things as the flow field several chord lengths away from the wing before a full explanation will emerge.